The message reads "Consider...". Below it, we see Melissa Leo looking positively, well, leonine. Or cougar-like, as the jargon might have it. To the untrained eye, this image – inserted by Leo into the Hollywood trade press this week as a full-page advert – resembles the mock-ups with which an ad agency might make the unsuccessful pitch for an account with a perfume company.

This is, of course, Leo's eccentric, self-financed attempt to swing votes her way for the best supporting actress Oscar. Hollywood is sniggering its head off. My colleague Jon Henley contributed an erudite short history of self-promotion the other day. He said it tends to backfire, and others seem to agree: Leo is reported to have hurt her chances by, as she might put it herself, "self-pimping".

I don't know whether she has or has not – at the time of writing, the results were not yet in – but I think she's kind of ballsy. And if the outcome was materially affected by her amusing piece of self-promotion, shame on the self-important boobies who run the Academy.

Leo's transgression – on realising that what with her being over 40, there's no chance that the ageist, sexist glossy magazines are going to do the pimping for her – was to do the pimping herself, rather than just sit quietly and take her lumps. Her cheering act of honest vulgarity has done no more than lay bare the device: self-pimping is what Hollywood is all about. Me! Me! Me!

It's one of the great peculiarities of the system that even though acting is supposed to be about effacing yourself and giving way to a character, the entire industry is predicated on the exact opposite – and has been ever since pox-raddled groundlings were queuing up to watch Burbage and Kemp at the Globe. People don't pay to see Dracula: they pay to see Gary Oldman prancing about in blue glasses and a cloak. John Wayne, the archetypal Hollywood star, is said once to have harrumphed something along the lines of "Acting? I don't know about acting. I just play Big John and that pretty much works for me."

All that "method" codswallop – I ask you. When you see Dustin Hoffman giving one of his bravura performances – something involving a lazy eye, or a limp – you don't forget it's Dustin Hoffman. If anything, he simply becomes all the more insufferably Dustin-Hoffmany. He becomes Dustin-Hoffman-Giving-A-Bravura-Performance. You sit there rapt, mouth full of popcorn, stroking your chin without even knowing you're doing it, and wondering if he'll get the Oscar, or if it'll be Philip Seymour Hoffman for that film where he becomes a man who looks a lot like Philip Seymour Hoffman, only with long hair and glasses.

Even as I was writing the paragraph above, someone reminded me of a Vanity Fair photoshoot that exactly – but exactly – proves my point. A photographer called Howard Schatz has set out to capture the very moment – like the beat of a hummingbird's wing – at which the magical thing we call "acting" takes place. Each photograph in the series In Character: Actors Acting shows a film star making three different faces according to a detailed brief.

So here, for example, are three photographs of Laurence Fishburne, taking on three different roles. Left: He's a broke, struggling screenwriter emerging from a pitch lunch at a Beverly Hills restaurant, just in time to see a landscaper's pickup back into his borrowed Lamborghini. Centre: He's a stoned, purely mercenary substitute teacher telling his third-graders, "Anyone who makes any noise while I'm resting will be sent home to Mommy in several little boxes." Right: He's a nerdy 11-year-old video gamer surrounded by BlizzCon posters and fellow nerds, taking this particular session of World of Warcraft way too seriously.

These, at least, are the back-stories Fishburne was given – but what do the photographs actually show? Left: Fishburne gurning with his mouth wide open. Middle: Fishburne gurning with his mouth half-open. Right: Fishburne gurning with his mouth so wide open you can see his breakfast and his eyes rolled back into his head.

The whole project is completely hilarious. Thirty or so globally respected actors, along with Ian McShane, were given complicated scenarios to internalise, and were then photographed looking like themselves with their mouths open. Most of acting, it appears from this photoshoot, is to do with how wide open your mouth is.

With skill and practice, one can capitalise on one's natural gifts in that department – it's surely no accident that Cameron Diaz and Julia Roberts look like they could each swallow a double-decker bus without it so much as clinking their teeth. But it's the self-pimping, on screen and off, that really counts. Whatever the Oscars results, Melissa Leo should hold her mouth half open and her head up high.